A top nuclear authority assured Friday that Rawatbhata's Rajasthan Atomic Power Station Unit-5 poses no radiation threat as there was no radioactive leakage into the environment.
On June 23, there was an incident of Tritium uptake due to an inadvertent rise in Tritium levels in a small area of the containment building of Unit-5, Nuclear Power Corporation of India Ltd (NPCIL) executive director N. Nagaich said.
"The incident occurred during a modification work being carried out, under the planned biennial shutdown of Unit-5, for assuring a provision alternate water addition to moderator system in that reactor," Nagaich said.
He said that this localized increase in Tritium concentration occurred due to the opening of the moderator cover gas line where the welding jobs were to be carried out.
"There was absolutely no release of radiation to the environment and the workers are continuing to perform their normal duties in other areas of the power station," Nagaich asserted.
He added that all persons involved in the work were monitored as a regular practice.
While two persons are likely to exceed the annual exposure limits specified by the regulatory body, the exposure of the other persons is below the specified limits, he assured.
Accordingly, these persons - who have not been identified - have been assigned work in non-radioactive areas as per prevailing procedures applicable in such incidents.
The NPCIL has reported the incident to the Atomic Energy Regulatory Board and is being separately investigated by both (NPCIL & AERB).
"The appropriate measures as suggested by these committees to prevent such incidents in future, will be implemented promptly," Nagaich said.
The RAPPS with six units has Pressurized Heavy Water Reactors, which use natural uranium as fuel.
Heavy Water, used as moderator and coolant in these reactors, is essentially as derivative of ordinary water which has a heavier isotope of hydrogen called deuterium.
Heavy Water is similar in appearance to ordinary water and is non-radioactive till it is used in a nuclear power reactor.
Tritium, a heavier isotope is formed from heavy water during operation of the plant, and small quantities of Tritium exist in the form of vapor in the reactor building.
Tritium is a soft beta emitter (of very low energy and can be stopped by a thin paper) and once it enters the body, as a natural process it comes out of the body within a week through urination and sweating, Nagaich explained.